Export of logical volumes by pools

ABSTRACT

A virtual tape server for implementing a method for exporting one or more logical volumes contained in a source physical volume pool. The method involves an activation of an export clone pool to clone an identity of the source physical volume pool into the export clone pool based on the logical volumes, an exportation of the export clone pool including the logical volumes subsequent to the activation of the export clone pool, and a deactivation of the export clone pool to purge the identity of the source physical volume pool from the export clone pool subsequent to the exportation of the export clone pool.

FIELD OF THE INVENTION

The present invention generally relates to data storage and processing,and in particular to virtual storage systems. The present inventionspecifically relates to a method and system for efficiently exportingremovable storage volumes from a virtual storage system.

BACKGROUND OF THE INVENTION

In hierarchical virtual storage systems, intensively used and frequentlyaccessed data is stored in fast but expensive memory. One example of afast memory is a direct access storage device (“DASD”). In contrast,less frequently accessed data is stored in less expensive but slowermemory. Examples of slower memory are tape drives and disk drive arrays.The goal of the hierarchy is to obtain moderately priced, high-capacitystorage while maintaining high-speed access to the stored information.

One such hierarchical storage system is a virtual tape storage system(“VTS”) including a host data interface, a DASD, and a number of tapedevices. When the host writes a logical volume, or a file, to the VTS,the data is stored as a file on the DASD. Although the DASD providesquick access to this data, it will eventually reach full capacity and abackup or secondary storage system will be needed. An IBM 3590 tapecartridge is one example of a tape device that could be used as a backupor secondary storage system.

When the DASD fills to a predetermined threshold, the logical volumedata for a selected logical volume is then appended onto a tapecartridge, or a physical volume, with the original left on the DASD forpossible cache hits. When a DASD file has been appended to a tapecartridge and the original remains on the DASD, the file is“premigrated.”

When the host reads a logical volume from the VTS, a cache hit occurs ifthe logical volume currently resides on the DASD. If the logical volumeis not on the DASD, the storage manager determines which of the physicaltape volumes contains the logical volume. The corresponding physicalvolume is then mounted on one of the tape devices, and the data for thelogical volume is transferred back to the DASD from the tape.

Typically, a database containing information that links the logicalvolumes to their corresponding physical tape volume is maintained by theVTS. Generally, the database is maintained and backed up separately fromthe data tapes. From time to time, the data tapes may need to beexported from a source VTS to a target VTS. Currently, exportation ofthe data tapes requires a copying of all of the data from all sourcetapes in the source VTS to all target tapes of the target VTS, which isinefficient in terms of data processing power and time. In fact, inwould be more efficient just to output all of the source tapes from thesource VTS as the target tapes for the target VTS, but this can beimpractical in terms of the continued operation of the source VTS.

Accordingly, what is needed in the art is an improved method forexporting data tapes from a source VTS to a target VTS that mitigatesthe above-discussed limitations in the prior art. More particularly,what is needed in the art is an improved method for exporting data tapesthat allows a continued host usage of the source tapes during a periodthe source tapes are being data copied from a remote cluster.

SUMMARY OF THE INVENTION

The present invention provides a new and unique export of logicalvolumes by pools.

A first form of the present invention is a computer bearing mediumtangibly embodying a program of machine-readable instructions executableby a processor to perform operations for exporting one or more logicalvolumes contained in a source physical volume pool. The operationscomprise an activation of an export clone pool to clone an identity ofthe source physical volume pool into the export clone pool based on thelogical volumes, an exportation of the export clone pool including theat least one logical volume subsequent to the activation of the exportclone pool, and a deactivation of the export clone pool to purge theidentity of the source physical volume pool from the export clone poolsubsequent to the exportation of the export clone pool.

A second form of the present invention is a virtual tape servercomprising a processor, and a memory storing instructions operable withthe processor for exporting one or more logical volumes contained in asource physical volume pool. The instructions are executed foractivating an export clone pool to clone an identity of the sourcephysical volume pool into the export clone pool based on the logicalvolumes, for exporting the export clone pool including the at least onelogical volume subsequent to the activation of the export clone pool,and for deactivating the export clone pool to purge the identity of thesource physical volume pool from the export clone pool subsequent to theexportation of the export clone pool.

A third form of the present invention is a method for exporting one ormore logical volumes contained in a source physical volume pool. Themethod comprises an activation of an export clone pool to clone anidentity of the source physical volume pool into the export clone poolbased on the logical volumes, an exportation of the export clone poolincluding the at least one logical volume subsequent to the activationof the export clone pool, and a deactivation of the export clone pool topurge the identity of the source physical volume pool from the exportclone pool subsequent to the exportation of the export clone pool.

The aforementioned forms and additional forms as well as objects andadvantages of the present invention will become further apparent fromthe following detailed description of the various embodiments of thepresent invention read in conjunction with the accompanying drawings.The detailed description and drawings are merely illustrative of thepresent invention rather than limiting, the scope of the presentinvention being defined by the appended claims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a basic embodiment of a virtual tape server inaccordance with the present invention;

FIG. 2 illustrates a flowchart representative of a basic embodiment of alogical volume export method in accordance with the present invention;

FIG. 3 illustrates an exemplary embodiment of the virtual tape serverillustrated in FIG. 1 in accordance with the present invention;

FIG. 4 illustrates a flowchart representative of an exemplary embodimentthe logical volume export method illustrated in FIG. 2 in accordancewith the present invention; and

FIGS. 5-9 illustrate exemplary operational states of volume poolsillustrated in FIG. 4 in accordance with an execution of the logicalvolume export method illustrated in FIG. 3.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIG. 1 illustrates a virtual tape system 10 employing a virtual volumecache 20, a tape library 30 having a library manager 31 for managing aplurality of physical volumes 32 stored on tapes therein, and a hostserver 40 for facilitating a host (not shown) in initiating and runninghost jobs for writing and copying physical volumes 32 as known in theart. The present invention addresses a host job directed to an export oflogical volumes (not shown) mapped to one or more physical volumes 32.To this end, host server 40 employs a processor 41 and a memory 42 forsupporting a pool manager 43 and an export manager 44.

Pool manager 43 is structurally configured to establish and maintain ascratch pool 50 of scratch volumes and one or more physical volume pools60 containing logical volumes stored on physical volumes 32 (e.g., tape)as known in the art. As would be appreciated by those having ordinaryskill in the art, each physical volume pool 60 typically has an X numberof pool rules, where X≧1, and a mapping of a Y number of logical volumesto a Z number of physical volumes, where Y≧Z≧1.

Pool manager 43 is further structurally configured to manage anactivation of an export clone pool 70 of the present invention forfacilitating an efficient export of logical volumes contained withinphysical volume pools 60 as requested by a host job in accordance with alogical volume export method of the present invention as will beexemplarily described herein in connection with FIG. 2. When exportclone pool 70 has been activated for export by pool manager 43, exportmanager 44 is structurally configured for executing an exportation ofthe logical volumes contained within physical volume pools 60 asrequested by the host job in accordance with the logical volume exportmethod of the present invention.

Specifically, FIG. 2 illustrates a flowchart 80 representative of thelogical volume export method of the present invention that is initiatedby pool manager 43 in response to a host job requesting an export oflogical volumes 62 contained with a source physical volume pool 60(S)among physical volume pools 60. A stage S82 of flowchart 80 encompassespool manager 43 activating export clone pool 70 to clone an identity ofthe source physical volume pool 60(S) into export clone pool 70. Forexample, as shown in stage S82, pool manager 43 copies each pool rule 61of source physical volume pool 60(S) as pool rules 71 (61) of exportclone pool 70. In one embodiment, pool rules 61 include informationnecessary for the management of the functioning interconnection betweenlogical volumes 62 and corresponding physical volumes contained insource physical volume pool 60(S), such as, for example, the type oftapes being used and data borrowing/return policies.

Additionally, as also shown in stage S82, pool manager 43 moves eachlogical volume 62 of source physical volume pool 60(S) into export clonepool 70. In one embodiment, the host job provides a listing of logicalvolumes 62 on an explicit basis and/or a physical volume basis wherebythe movement of logical volumes 62 from source physical volume pool60(S) to export clone pool 70 is based on the listing of logical volumes62 in view of a snapshot of source physical volume pool 60(S) at thetime of export request by the host job. Specifically, the movement oflogical volumes 62 from source physical volume pool 60(S) to exportclone pool 70 can be accomplished by a selective use of two (2)procedures that is based on the physical volume location of logicalvolumes 62 within source physical volume pool 60(S) as established bythe snapshot of source physical volume pool 60(S) at the time of exportrequest by the host job.

The first procedure involves pool manager 43 executing a recall of anindividual logical volume 62 from a physical volume of source physicalvolume pool 60(S) to cache 20 (FIG. 1) whereby the recalled individuallogical volume 62 is premigrated from cache 20 to a physical volume ofexport clone pool 70 (e.g., a scratch volume of export clone pool 70).While this first procedure can be used for any reason, it is primarilyappropriate to use this first procedure in response to the individuallogical volume 62 being explicitly listed by the host job and beingcontained within a physical volume containing a non-zero number of thelisted logical volumes 62 where the physical volume has a size or aquantity that is less than a predefined size threshold or a predefinedquantity threshold, respectively, as indicated by the snapshot of sourcephysical volume pool 60(S).

The second procedure involves pool manager 43 executing a databaseoperation for moving a physical volume of source physical volume pool60(s) to export clone pool 70 where the moved physical volume a non-zeronumber of the listed logical volumes 62. While this second procedure canalso be used for any reason, it is primarily appropriate to use thissecond procedure in response to the physical volume being explicitlylisted by the host job and/or the physical volume containing a non-zeronumber of the listed logical volumes 62 where the physical volume has asize or a quantity that is greater than a predefined size threshold or apredefined quantity threshold, respectively, as indicated by thesnapshot of source physical volume pool 60(S).

In either case, any movement of the physical volume can further involvea removal of any superfluous logical volume of the physical volume(i.e., a logical volume contained with the physical volume that is notbeing requested by the host job) prior to moving the physical volume toexport clone pool 70. The removal can be accomplished by a recall ofeach superfluous logical volume of the physical volume from sourcephysical volume pool 60(S) to cache 20 whereby each recalled superfluouslogical volume is premigrated back to source physical volume pool 60(S).

Alternatively, any movement of the physical volume can further involve areturn of any superfluous logical volume of the physical volumesubsequent to moving the physical volume from source physical volumepool 60(S) to export clone pool 70. The return can be accomplished by arecall of each superfluous logical volume of the physical volume fromexport clone pool 70 to cache 20 whereby each recalled superfluouslogical volume is premigrated back to source physical volume pool 60(S).

Upon a complete activation of export clone pool 70, a stage S84 offlowchart 80 encompasses export manager 44 executing an exportation ofexport clone pool 70 in accordance with the host job. The exportation ofexport clone pool 70 includes known exporting acts by export manager 44that are omitted from description herein. The portion of the exportationof export clone pool 70 relevant to the present invention involves apre-export phase of stage S84. Specifically, subsequent to theactivation of export clone pool 70 by pool manager 30 as shown in stageS84, export manager 44 writes data 73 residing in cache 20 (FIG. 1) toexport clone pool 70 that was cached prior to the database snapshot ofsource physical volume pool(S) 60 and is associated with the clonedlogical volumes 62. Furthermore, as shown in stage S84, export manager44 facilitates a writing of data 63 residing in cache 20 to physicalvolume pool 60 subsequent to the database snapshoot of source physicalvolume pool 60(S).

Upon completing the cache data write to logical volume 62 within exportclone pool 70, export manager 44 writes a table of contents at the endof each physical volume of export control pool 70 that contains anynumber of logical volumes 62. The table of contents for each physicalvolume preferably includes information describing the contents of thephysical volume and may include information describing a set of physicalvolumes.

Upon completing the writing of the table of contents, export manager 44completes the exporting of the physical volumes of export clone pool 70corresponding to logical volumes 62. Thereafter, during a stage S86 offlowchart 80, pool manager 43 deactivates export clone pool 70 to purgethe identity of source physical volume pool 60(S) from export clone pool70. In one embodiment, as shown in stage S86, pool rules 71 (61) aredeleted from export clone pool 70 and any logical volume 62 that failedto be exported is returned to source physical volume pool 60(S) by adatabase movement of a corresponding physical volume from export clonepool 70 to source physical volume pool 60(S).

In practice, the present invention does not impose any limitations orany restrictions to the structural configuration of virtual tape server10 as shown in FIG. 1 or any deviation thereof. To facilitate a furtherunderstanding of the present invention, an exemplary embodiment ofvirtual tape server 10 will now be described herein in connection withFIG. 3.

Referring to FIG. 3, an exemplary virtual tape server 11 employs virtualvolume cache 20 (FIG. 1), tape library (FIG. 1), and a host server 90including a virtualization node 100 and a hierarchical storage node 110having a cluster manager 111, a remote file access server 112, a datamover 113, a physical tape manager 114, a cache manager 115, a recallmanager 116, a database 117, a management interface 118 and a mediamanager 119.

Virtualization node 100 includes tape daemons (not shown) emulating atape drive (e.g., IBM 3490 tape drive) to a host (not shown). In oneembodiment, virtualization node 100 operates on a file that is either oncache 20 or operates on a remote cluster's cache (not shown) throughremote file access server 112. Cluster manager 111 coordinatesoperations between clusters via tokens that are stored in each cluster'sdatabase 117 to determine which cluster has a current copy of data andcoordinates coping of data between clusters.

Remote file access server 112 provides a link to cache 20 by an remotecluster. Data mover 113 controls the actual data transfer operations forcopies performed between clusters and transfers of data between cache 20and library 30. Physical tape manager 114 manages physical tapes inlibrary 30 in multiple physical volume pools, controls reclamation,borrows/returns volumes from a scratch pool, and controls movement oftapes between pools. Cache manager 115 controls a copying of databetween cache 20 to library 30 and any subsequent removal of a redundantcopy of data in cache 20, and provides control signals to balance dataflow between cache 20 and other node 110 components. Recall managerqueues and controls recalls of data into cache 20 from library 30 onbehalf of virtualization node 100 or cluster manager 111.

Management interface 118 provide information about server 11 and allowsa user control and configuration of system 11. Media manager 119 managesthe handling of physical tapes and error recovery, and diagnoses errorsand determines if the errors were caused by a physical tape drive or aphysical tape media to thereby take appropriate action.

FIG. 4 illustrates a flowchart 120 representative of the logical volumeexport method of the present invention that is initiated byvirtualization node 100 in response to a host job directed to an exportof a set of logical volumes. For purposes of facilitating anunderstanding of the logical volume export method of the presentinvention, flowchart 120 is described herein in the context of FIG. 5,which illustrates a scratch pool 140, a physical volume pool 150, aphysical volume pool 160, and a deactivated export clone pool 170.Scratch pool 140 has six (6) empty scratch volumes V01-V06. Physicalvolume pool 150 has pool rules 151, four (4) full physical volumesV11-V14, a partially full physical volume V15 and an empty physicalvolume V16. Physical volume pool 160 has pool rules 161, three (3) fullphysical volumes V21-V23, a partially full physical volume V24, and apair of empty physical volumes V25 and V26. Export clone pool 170 iscompletely vacant in its deactivated state.

For flowchart 120, physical volumes V21-V24 of physical volume pool 160will be the export subject of the host job.

As shown in FIG. 4, a stage S122 of flowchart 120 encompasseshierarchical storage node 110 activating export clone pool 170 to clonean identity of source physical volume pool 160 by copying pool rules 161as pool rules 171 (161) and by moving physical volumes V21-V24 to exportclone pool based on a database snapshot of physical volume pool 160 atthe time of the export request. Additionally, in anticipation of any newdata writes to export clone pool 170 based on the logical volumescontained within physical volumes V21-V24, pair of scratch volumes V05and V06 are moved from scratch pool 140 to export clone pool 170 asempty physical volumes V35 and V36.

The first procedure involves hierarchical storage node 110 executing arecall of logical volume RLV from physical volumes V21-V24 to cache 20(FIG. 1) as shown in FIG. 6 whereby each recalled individual logicalvolume RLV is premigrated from cache 20 to a physical volume of exportclone pool 170 (e.g., scratch volume V35 and V36 of export clone pool170). While this first procedure can be used for any reason, it isprimarily appropriate to use this first procedure in response to anindividual logical volume being explicitly listed by the host job andbeing contained within a physical volume among physical volumes V21-V24that contains a non-zero number of the listed logical volumes where thephysical volume has a size or a quantity that is less than a predefinedsize threshold or a predefined quantity threshold, respectively, asindicated by the snapshot of physical volume pool 160.

The second procedure involves hierarchical storage node 110 executing adatabase operation for moving physical volumes V21-V24 of sourcephysical volume pool 160 to export clone pool 70. While this secondprocedure can also be used for any reason, it is primarily appropriateto use this second procedure in response to physical volumes V21-V24being explicitly listed by the host job and/or physical volumes V21-V24containing a non-zero number of the listed logical volumes wherephysical volumes V21-V24 have a size or a quantity that is greater thana predefined size threshold or a predefined quantity threshold,respectively, as indicated by the snapshot of source physical volumepool 160.

In either case, any movement of physical volumes V21-V24 can furtherinvolve a removal of any superfluous logical volume SLV1 of physicalvolumes V21-V24 prior to moving physical volumes V21-V24 to export clonepool 170. As shown in FIG. 6, the removal can be accomplished by arecall of each superfluous logical volume SLV1 of physical volumesV21-V24 from source physical volume pool 160 to cache 20 whereby eachrecalled superfluous logical volume SLV1 is premigrated back to sourcephysical volume pool 160.

Alternatively, any movement of physical volumes V21-V24 can furtherinvolve a return of any superfluous logical volume of the physicalvolume subsequent to moving physical volumes V21-V24 from sourcephysical volume pool 160 to export clone pool 70. As shown in FIG. 6,the return can be accomplished by a recall of each superfluous logicalvolume SLV2 of physical volumes V21-V24 from export clone pool 70 tocache 20 whereby each recalled superfluous logical volume SLV2 ispremigrated back to source physical volume pool 160.

Stages S124 and S126 of flowchart 120 will be subsequently describedherein in the context of physical volumes V21-V24 being moved to exportclone pool 170 within a need for recalling and premigrating any logicalvolumes of physical volumes V21-V24.

As such, upon updating database 117 (FIG. 3) as needed, stage S124 offlowchart 120 encompasses hierarchical storage node 110 executing anexportation of physical volumes V21-V24 contained within export clonepool 70. As shown in FIG. 7, a pre-export phase of stage S124 involveshierarchical storage node 10 targeting export copy data 200corresponding to physical volumes V21-V24 and residing in cache 20 priorto the database snapshot of source physical volume pool 160 while stillmaintaining a host write/copy data 180 to physical volume pool 150 and ahost write/copy data 190 to source physical volume pool 160. Ifrequired, export data will be written to scratch volumes V35 and V36 andadditional scratch volumes will be borrowed from scratch pool 140.

Stage S126 further encompasses hierarchical storage node 110 markingphysical volume V24 as full upon completion of export copy data write200 as shown in FIG. 8, and updating a table of contents of each fullphysical volume V21-V24 of export clone pool 170 to reflect its contentsand any other pertinent information. Stage S126 further includesadditional processing steps (not shown) known in the art for exportingphysical volumes V21-V24.

As shown in FIG. 9, upon completion of the export of physical volumesV21-V24, stage S126 of flowchart 120 encompasses hierarchical storagenode 110 deactivating export clone pool 170 to purge the identity ofsource physical volume pool 160 from export clone pool 170 by deletingpool rules 171 (161). In the case of a completion of the export ofphysical volumes V21-V23 with a failure of exporting physical volumeV24, stage S128 would further encompass hierarchical storage node 110moving failed physical volume V24 back to physical volume pool 160 asshown in FIG. 9.

Referring to FIGS. 1-9, those having ordinary skill in the art willappreciate numerous advantages of the present invention including, butnot limited to, an efficient export of logical volumes that timely andcompletely achieve the export without any interference withwriting/copying operation of the VTS and with minimal loss of data.Those having ordinary skill in the art will further recognize that thetarget VTS the export data is prepared for may be the source VTS or maynot be a specific VTS at all, with the target tapes being sent to asecure offline storage location for disaster recovery. Those havingordinary skill in the art will further appreciate how to apply theinventive principles of the present invention to more or less complexstorage environments that shown in FIGS. 1-9.

The term “processor” as used herein is broadly defined as one or moreprocessing units of any type for performing all arithmetic and logicaloperations and for decoding and executing all instructions related tofacilitating an implementation by a virtual tape server of the variouslogical volume export methods of the present invention. Additionally,the term “memory” as used herein is broadly defined as encompassing allstorage space in the form of computer readable mediums of any typewithin the virtual tape server.

Those having ordinary skill in the art of logical volume exporttechniques may develop other embodiments of the present invention inview of the inventive principles of the present invention describedherein. The terms and expression which have been employed in theforegoing specification are used herein as terms of description and notof limitations, and there is no intention in the use of such terms andexpressions of excluding equivalents of the features shown and describedor portions thereof, it being recognized that the scope of the inventionis defined and limited only by the claims which follow.

1. A computer bearing medium tangibly embodying a program ofmachine-readable instructions executable by a processor to performoperations, the operations comprising: maintaining a source physicalvolume pool corresponding to a plurality of logical volumes; activatingan export clone pool to clone an identity of the source physical volumepool into the export clone pool based on at least one logical volume,wherein the source physical volume pool includes at least one pool rule,wherein the activation of the export clone pool to clone the identity ofthe source physical volume pool into the export clone pool based on theat least one logical volume includes copying the at least one pool ruleof the source physical volume pool to the export clone pool, wherein theat least one pool rule indicates a type of storage device being used,wherein the at least one pool rule indicates data borrowing and datareturn policies, and wherein the export clone pool and the sourcephysical volume pool are maintained in a first computational device;exporting, from the first computational device to a second computationaldevice, at least some logical volumes of the plurality of logicalvolumes of the export clone pool including the at least one logicalvolume subsequent to the activation of the export clone pool, wherein anattempt to export at least one selected logical volume of the pluralityof logical volumes from the export control pool causes a failure,wherein the source physical volume pool is configured to be used by thefirst computational device while the exporting from the export clonepool to the second computational device is being performed; anddeactivating the export clone pool to purge the identity of the sourcephysical volume pool from the export clone pool subsequent to theexportation of the export clone pool, and in response to the failure inthe export of the at least one selected logical volume from the exportcontrol pool, moving the at least one selected logical volume from theexport control pool to the source physical volume pool, wherein inresponse to determining that it is necessary to write export data toscratch volumes and borrow additional scratch volumes from a scratchpool, the export data is written to the scratch volumes and theadditional scratch volumes are borrowed from the scratch pool.
 2. Thecomputer bearing medium of claim 1, wherein the at least one pool ruleindicates information to manage a functioning interconnection betweenthe at least one logical volume and a corresponding physical volumecontained in the source physical volume pool, and wherein thedeactivation of the export pool to purge the identity of the sourcephysical volume pool from the export clone pool subsequent to theexportation of the export clone pool includes: deleting the least onecopied pool rule from the export clone pool.
 3. The computer bearingmedium of claim 1, wherein the activation of the export pool to clonethe identity of the source physical volume pool into the export clonepool based on the at least one logical volume includes: individuallymoving each logical volume of the at least one logical volume from thesource physical volume pool to the export clone pool.
 4. The computerbearing medium of claim 1, wherein the source physical volume poolincludes at least one physical volume containing the at least onelogical volume; and wherein the activation of the export pool to clonean identity of the source physical volume pool into the export clonepool based on the at least one logical volume includes: moving the atleast one physical volume from the source physical volume pool to theexport clone pool.
 5. The computer bearing medium of claim 4, whereinthe activation of the export pool to clone the identity of the sourcephysical volume pool into the export clone pool based on the at leastone logical volume further includes: removing any superfluous logicalvolume from the at least one physical volume prior to moving the atleast one physical volume from the source physical volume pool to theexport clone pool.
 6. The computer bearing medium of claim 4, whereinthe activation of the export pool to clone the identity of the sourcephysical volume pool into the export clone pool based on the at leastone logical volume further includes: returning any superfluous logicalvolume of the at least one physical volume from the export clone pool tothe source physical volume pool subsequent to moving the at least onephysical volume from the source physical volume pool to the export clonepool.
 7. The computer bearing medium of claim 1, wherein the exportationof the export clone pool including the at least one logical volumesubsequent to the activation of the export clone pool includes: prior toexporting the export clone pool, writing any cached data associated withthe at least one logical volume to the export clone pool based on thedata being cached prior to an activation of the export clone pool.
 8. Avirtual tape server, comprising: a processor; and a memory storinginstructions operable with the processor, the instructions executed for:maintaining a source physical volume pool corresponding to a pluralityof logical volumes; activating an export clone pool to clone an identityof the source physical volume pool into the export clone pool based onat least one logical volume, wherein the source physical volume poolincludes at least one pool rule, wherein the activation of the exportclone pool to clone the identity of the source physical volume pool intothe export clone pool based on the at least one logical volume includescopying the at least one pool rule of the source physical volume pool tothe export clone pool, wherein the at least one pool rule indicates atype of storage device being used, wherein the at least one pool ruleindicates data borrowing and data return policies, and wherein theexport clone pool and the source physical volume pool are maintained inthe virtual tape server, wherein the virtual tape server comprises afirst computational device; exporting, from the first computationaldevice to a second computational device, at least some logical volumesof the plurality of logical volumes of the export clone pool includingthe at least one logical volume subsequent to the activation of theexport clone pool, wherein an attempt to export at least one selectedlogical volume of the plurality of logical volumes from the exportcontrol pool causes a failure, wherein the source physical volume poolis configured to be used by the first computational device while theexporting from the export clone pool to the second computational deviceis being performed; and deactivating the export clone pool to purge theidentity of the source physical volume pool from the export clone poolsubsequent to the exportation of the export clone pool, and in responseto the failure in the export of the at least one selected logical volumefrom the export control pool, moving the at least one selected logicalvolume from the export control pool to the source physical volume pool,wherein in response to determining that it is necessary to write exportdata to scratch volumes and borrow additional scratch volumes from ascratch pool, the export data is written to the scratch volumes and theadditional scratch volumes are borrowed from the scratch pool.
 9. Thevirtual tape server of claim 8, wherein the at least one pool ruleindicates information to manage a functioning interconnection betweenthe at least one logical volume and a corresponding physical volumecontained in the source physical volume pool, and wherein thedeactivation of the export pool to purge the identity of the sourcephysical volume pool from the export clone pool subsequent to theexportation of the export clone pool includes: deleting the least onecopied pool rule from the export clone pool.
 10. The virtual tape serverof claim 8, wherein the activation of the export pool to clone theidentity of the source physical volume pool into the export clone poolbased on the at least one logical volume includes: individually movingeach logical volume of the at least one logical volume from the sourcephysical volume pool to the export clone pool.
 11. The virtual tapeserver of claim 10, wherein the source physical volume pool includes atleast one physical volume having the at least one logical volume; andwherein the activation of the export pool to clone the identity of thesource physical volume pool into the export clone pool based on the atleast one logical volume includes: moving the at least one physicalvolume from the source physical volume pool to the export clone pool.12. The virtual tape server of claim 11, wherein the activation of theexport pool to clone the identity of the source physical volume poolinto the export clone pool based on the at least one logical volumefurther includes: removing any superfluous logical volume from at leastone physical volume prior to moving the at least one physical volumefrom the source physical volume pool to the export clone pool.
 13. Thevirtual tape server of claim 10, wherein the activation of the exportpool to clone the identity of the source physical volume pool into theexport clone pool based on the at least one logical volume furtherincludes: returning any superfluous logical volume of the at least onephysical volume from the export clone pool to the source physical volumepool subsequent to moving the at least one physical volume from thesource physical volume pool to the export clone pool.
 14. The virtualtape server of claim 8, wherein the exportation of the export clone poolincluding the at least one logical volume subsequent to the activationof the export clone pool: writing any cached data associated with the atleast one logical volume to the export clone pool based on the databeing cached prior to an activation of the export clone pool.
 15. Amethod, comprising: maintaining a source physical volume poolcorresponding to a plurality of logical volumes; activating an exportclone pool to clone an identity of the source physical volume pool intothe export clone pool based on at least one logical volume, wherein thesource physical volume pool includes at least one pool rule, wherein theactivation of the export clone pool to clone the identity of the sourcephysical volume pool into the export clone pool based on the at leastone logical volume includes copying the at least one pool rule of thesource physical volume pool to the export clone pool, wherein the atleast one pool rule indicates a type of storage device being used,wherein the at least one pool rule indicates data borrowing and datareturn policies, and wherein the export clone pool and the sourcephysical volume pool are maintained in a first computational device;exporting, from the first computational device to a second computationaldevice, at least some logical volumes of the plurality of logicalvolumes of the export clone pool including the at least one logicalvolume subsequent to the activation of the export clone pool, wherein anattempt to export at least one selected logical volume of the pluralityof logical volumes from the export control pool causes a failure,wherein the source physical volume pool is configured to be used by thefirst computational device while the exporting from the export clonepool to the second computational device is being performed; anddeactivating the export clone pool to purge the identity of the sourcephysical volume pool from the export clone pool subsequent to theexportation of the export clone pool, and in response to the failure inthe export of the at least one selected logical volume from the exportcontrol pool, moving the at least one selected logical volume from theexport control pool to the source physical volume pool, wherein inresponse to determining that it is necessary to write export data toscratch volumes and borrow additional scratch volumes from a scratchpool, the export data is written to the scratch volumes and theadditional scratch volumes are borrowed from the scratch pool.
 16. Themethod of claim 15, wherein the at least one pool rule indicatesinformation to manage a functioning interconnection between the at leastone logical volume and a corresponding physical volume contained in thesource physical volume pool, and wherein the deactivation of the exportpool to purge the identity of the source physical volume pool from theexport clone pool subsequent to the exportation of the export clone poolincludes: deleting the least one copied pool rule from the export clonepool.
 17. The method of claim 15, wherein the activation of the exportpool to clone an identity of the source physical volume pool into theexport clone pool based on the at least one logical volume includes:individually moving each logical volume of the at least one logicalvolume from the source physical volume pool to the export clone pool.18. The method of claim 17, wherein the source physical volume poolincludes at least one physical volume having the at least one logicalvolume; and wherein the activation of the export pool to clone theidentity of the source physical volume pool into the export clone poolbased on the at least one logical volume includes: moving the at leastone physical volume from the source physical volume pool to the exportclone pool.
 19. The method of claim 18, wherein the activation of theexport pool to clone the identity of the source physical volume poolinto the export clone pool based on the at least one logical volumefurther includes: removing any superfluous logical volume from at leastone physical volume prior to moving the at least one physical volumefrom the source physical volume pool to the export clone pool.
 20. Themethod of claim 17, wherein the activation of the export pool to clonethe identity of the source physical volume pool into the export clonepool based on the at least one logical volume further includes:returning any superfluous logical volume of the at least one physicalvolume from the export clone pool to the source physical volume poolsubsequent to moving the at least one physical volume from the sourcephysical volume pool to the export clone pool.
 21. The method of claim15, wherein the exportation of the export clone pool including the atleast one logical volume subsequent to the activation of the exportclone pool: writing any cached data associated with the at least onelogical volume to the export clone pool based on the data being cachedprior to an activation of the export clone pool.